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#1
November 11th 04, 02:48 PM
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SS Belt Drive?
A couple riders have brought up a discussion on chainwear recently.
That made me recall a Jericho SS showing off a belt drive they called 'Red October'. I've also seen them on Strida folding bikes. I'm sure it's not a new concept. Anybody out there actually riding a belt? I'm curious about pros and cons. If they're trusted on motorcycles, why not bikes? You'd think the drivetrain would last forever. /s 
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#2
November 11th 04, 06:03 PM
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#4
November 11th 04, 06:27 PM
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On Thu, 11 Nov 2004 18:21:17 +0000, Zog The Undeniable
wrote: wrote: On 11 Nov 2004 06:48:44 -0800, (supabonbon) wrote: A couple riders have brought up a discussion on chainwear recently. That made me recall a Jericho SS showing off a belt drive they called 'Red October'. I've also seen them on Strida folding bikes. I'm sure it's not a new concept. Anybody out there actually riding a belt? I'm curious about pros and cons. If they're trusted on motorcycles, why not bikes? You'd think the drivetrain would last forever. /s Dear SBB, One objection to a belt drive is that it won't work with the derailleur system. If this is overcome by the use of a motorcycle-style internal gear system, then the problem is that a belt drive is less efficient at transmitting a bicycle's feeble power than a chain drive. Most belts are also endless for maximum strength, so you'd need raised chainstays or a monostay design to avoid having to loop the belt round the frame. But belts can be pretty efficient - probably as good as a dirty chain [1] and quiet. [1] the inherent problem being that flexing rubbery things always involves a loss of energy - it's called hysteresis. But how efficient is your chain after 200 miles on wet roads? Dear Zog, Surprisingly, the efficiency of chains suffers hardly at all due to grime or lack of lubrication--those evils affect longevity. For efficiency, it's sprocket size and tension that matter: [long quote begins] The researchers found two factors that seemed to affect the bicycle chain drive's efficiency. Surprisingly, lubrication was not one of them. "The first factor was sprocket size," Spicer says. "The larger the sprocket, the higher the efficiency we recorded." The sprocket is the circular plate whose teeth catch the chain links and move them along. Between the front and rear sprockets, the chain links line up straight. But when the links reach the sprocket, they bend slightly as they curl around the gear. "When the sprocket is larger, the links bend at a smaller angle," Spicer explains. "There's less frictional work, and as a result, less energy is lost." The second factor that affected efficiency was tension in the chain. The higher the chain tension, Spicer says, the higher the efficiency score. "This is actually not in the direction you'd expect, based simply on friction," he says. "It's not clear to us at this time why this occurs." The Johns Hopkins engineers made another interesting discovery when they looked at the role of lubricants. The team purchased three popular products used to "grease" a bicycle chain: a wax-based lubricant, a synthetic oil and a "dry" lithium-based spray lubricant. In lab tests comparing the three products, there was no significant difference in energy efficiency. "Then we removed any lubricant from the chain and ran the test again," Spicer recalls. "We were surprised to find that the efficiency was essentially the same as when it was lubricated." The researcher speculates that a bicycle lubricant does not play a critical role under clean lab conditions, using a brand new chain. But it may contribute to energy efficiency in the rugged outdoors. "The role of the lubricant, as far as we can tell, is to take up space so that dirt doesn't get into the chain," Spicer says. "The lubricant is essentially a clean substance that fills up the spaces so that dirt doesn't get into the critical portions of the chain where the parts are very tightly meshed. But in lab conditions, where there is no dirt, it makes no difference. On the road, we believe the lubricant mostly assumes the role of keeping out dirt, which could very well affect friction in the drive train." http://www.jhu.edu/news_info/news/ho...ug99/bike.html Carl Fogel
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#5
November 11th 04, 07:12 PM
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#6
November 11th 04, 08:30 PM
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On Thu, 11 Nov 2004 19:12:16 +0000, Zog The Undeniable
wrote: wrote: Surprisingly, the efficiency of chains suffers hardly at all due to grime or lack of lubrication--those evils affect longevity. For efficiency, it's sprocket size and tension that matter: [long quote begins] The researchers found two factors that seemed to affect the bicycle chain drive's efficiency. Surprisingly, lubrication was not one of them. I saw that link too, but what about dirt and rust? Surely this increases the friction between the outer and inner plates a *lot*? Dear Zog, I doubt that many of us are riding road bicycles with chains rusty or grimy enough to make a noticeable difference in transmission efficiency. For those hypothetical few whose chains may have become hard-to-pedal rusty anchors, the obvious solution is a new $12 chain (less at WalMart). Sprocket-size and tension are the main things that affect chain-drive efficiency. Lubrication and cleanliness affect wear rates. Even when worn, chains are efficient at power transmission (until the point where they simply skip off the gears). Belt drives start out as a less efficient transmission and stay that way until they fail, usually catastrophically. Carl Fogel
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#7
November 11th 04, 08:56 PM
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If they're trusted on motorcycles, why not bikes? You'd think the drivetrain would last forever. Most of my MC riding buds have belt-drive's on thier MC's that last 10's of thousands of miles.... I'd certainly give it a try on the 29"er Disc SS, since it is about as much of an oddball bike as you cna uild these days. -- ITSN Gunterman USN Life, Liberty, and the pursuit of all who threaten it.
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#8
November 11th 04, 08:57 PM
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#9
November 11th 04, 09:03 PM
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On Thu, 11 Nov 2004 19:12:16 +0000, Zog The Undeniable
wrote: wrote: Surprisingly, the efficiency of chains suffers hardly at all due to grime or lack of lubrication--those evils affect longevity. For efficiency, it's sprocket size and tension that matter: [long quote begins] The researchers found two factors that seemed to affect the bicycle chain drive's efficiency. Surprisingly, lubrication was not one of them. I saw that link too, but what about dirt and rust? Surely this increases the friction between the outer and inner plates a *lot*? Only for a short time, until the conflicting surfaces wear each other to a state of clearance, and then it's not a factor anymore. I've observed this a number of times on junkyard bikes that have passed through my hands; if the chain seems stiff, I lube it, ride around the block a few times, and recheck for stiffness and wear. Most of the time, the stiffness is gone. Sometimes the chain is still within useful limits of wear as well. (Needless to say, many of the bikes which I see are something other than fresh from the factory, and have not been given much in the way of maintenance. I become better acquainted with the limits of neglect every day.) -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts.
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#10
November 11th 04, 09:18 PM
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